The invention relates to apparatus for minimizing fuel consumption in a refinery furnace by maintaining stack oxygen content at a low level under operating constraints, and more particularly relates to apparatus for controlling stack oxygen content in relation to operator input of targeted excess stack oxygen.
In recent years the use of apparatus for controlling various technical processes such as chemical processes for distillation, extraction and refining of petroleum and the like, has been developed. Certain variables of the process are measured and certain inputs controlled to enable the process to be driven in a more economical manner.
With respect to combustion processes in process furnaces, and the like, apparatus has been provided for conrolling the air supplied to the furnace, close to the requirement for combustion in order to minimize heat loss to flue gas. Such apparatus have included large-scale analog or digital calculating machines which utilize values of measured variables for automatically adjusting the air supplied to the furnace.
All such large scale computer systems of this type, however, involve very expensive equipment. Thus, it would be highly welcomed if a simplified and reliable system were developed.